Illness anxiety predicts higher mental strain and vaccine willingness-A nine-wave longitudinal study during the first 1.5 years of the COVID-19 pandemic in Germany.

Illness anxiety may amplify vulnerability to psychopathological symptoms during the COVID-19-pandemic-perhaps especially at the beginning of the pandemic and during high infection waves, but empirical evidence on this is lacking. In addition, considering a potentially functional facet of it, illness anxiety might be associated with higher vaccine willingness. We analyzed data of a nine-wave longitudinal online-survey (March 2020-October 2021) with 8148 non-probability sampled adults of the general population in Germany (clinicaltrials.gov: NCT04331106). Using multilevel analysis, we investigated longitudinal associations of dimensionally assessed illness anxiety (worry about illness, bodily preoccupation) with mental strain and vaccine willingness and considered the dynamic of the pandemic (i.e., duration and infection rates). Higher worry about illness and bodily preoccupation were associated with higher COVID-19-related fears, unspecific anxiety, depressive symptoms, and vaccine willingness. Vaccine willingness increased over time and in parallel to higher infection rates. Symptoms of mental strain decreased with continuing duration of the pandemic but increased when infection rates inclined. This decrease and increase, respectively, was steeper in individuals with higher illness anxiety. Our findings suggest that individuals with higher illness anxiety are more vulnerable to experience psychopathological symptoms during the ongoing pandemic, particularly at its beginning and during times of high infection rates. Thus, illness anxiety and associated symptoms should be targeted by adaptive measures. The fluctuation of symptoms parallel to the pandemic situation implies that support should be particularly issued at the beginning of extraordinary situations as well as during phases of high infection rates.